What type of application involves spraying solutions that are injected into the ground to reach foliage?

The type of application that involves injecting solutions into the ground to reach foliage is accurately described by foliar applications. This technique focuses on targeting plant leaves directly with solutions that are either sprayed or otherwise applied, allowing for efficient uptake of nutrients or pesticides through the leaves.

In the context of the question, while foliar applications do indeed involve the application of substances to the foliage, techniques like directed-spray treatments or band treatments refer to more specific methods that focus on the manner of application rather than emphasizing soil injection to target foliage. Ground applications typically cover a broader scope and include various techniques but do not specifically indicate the injection method that is key to reaching foliage effectively. Hence, foliar applications are the most precise answer that aligns with the method described in the question.